Furnace and heat storage assembly

Abstract

A furnace and associated heat storage assembly includes a firebox arranged within a rock storage area that incorporates a recirculating flue arrangement for returning unburned gases to below a fuel grate for mixing with fresh inlet air. The rock in the heat storage area is heated by conduction of heat from the firebox, circulating flue gases and a smoke exhaust flue. Inlet air is preheated. An open grate arrangement provides for efficient burning of solid as-producing fuel. A system for circulating air and/or liquid through the rock can be provided, as can a water storage tank.

I claim: 
     
       1. A furnace and heat storage assembly comprising: a firebox with a bottom to support burning of a combustible material therein, and having a top plate to collect unburned combustible gases found in a lighter gas fraction zone above a heavier burned gas fraction zone;   an unburned gas recirculating flue with an open inlet end in communication with the lighter gas fraction zone, and an open exhaust end in communication with the firebox bottom;   fresh air supply means for injecting a supply of fresh air into said firebox to support combustion therein;   means for preheating an air flow through said fresh air supply means prior to its passage into said firebox; and   an exhaust flue for removing the heavier gas fraction from the interior of the firebox having: an open inlet end in communication with the interior of the firebox mounted above the combustible material proximate the heavier burned gas fraction zone, and an exhaust end in communication with the ambient environment.   
     
     
       2. A furnace and heat storage assembly according to claim 1, further including: a grate mounted in the firebox to support burning of a combustible material formed to provide open areas therethrough to freely pass ash, which grate has a flat center section with wings secured along opposite sides thereof that extend upwardly at obtuse angles from the plane of said center section.   
     
     
       3. A furnace and heat storage assembly according to claim 1, including means for maintaining a heat absorbing material proximate said firebox to absorb heat therefrom. 
     
     
       4. A furnace and heat storage assembly according to claim 3, wherein rock is arranged within said means for maintaining a heat absorbing material to absorb heat transferred from the unburned gas recirculating flue and the exhaust flue. 
     
     
       5. A furnace and heat storage assembly according to claim 4, wherein the means for preheating the air flow consists of a fresh air supply means in heat transfer relationship with the rock. 
     
     
       6. A furnace and heat storage assembly according to claim 5, wherein themeans for maintaining a heat absorbing material comprise: block walls which surround all but an accessible face of the firebox;   the fresh air supply means is a pipe that extends from an air flow control arranged at said accessible face of the firebox, over said firebox, and lengthwise into said firebox; and   the portion of said pipe within said firebox has a plurality of openings therein.   
     
     
       7. A furnace and heat storage assembly according to claim 1, wherein the unburned gas recirculating flue consists of open tubular members that intersect the opposite sides of the firebox, proximate the top thereof, connect into a discharge tube that passes across said firebox, below the combustion zone of the furnace, which discharge tube has openings formed therein for passing unburned gas into admixture with fresh air. 
     
     
       8. A furnace and heat storage assembly according to claim 3, further including means for circulating an air flow through the heat absorbing material to retrieve heat therefrom. 
     
     
       9. A furnace and heat storage assembly according to claim 8, wherein the means for circulating an air flow consists of, a vent opening formed in the means for maintaining a heat absorbing material;   a second opening formed in said means for maintaining a heat absorbing material; and   fan means arranged in said second opening to draw an air flow from said vent opening through the heat absorbing material.   
     
     
       10. A furnace and heat storage assembly according to claim 3, further including means for transferring heat from the heat absorbing material into a water circulation system. 
     
     
       11. A furnace and heat storage assembly according to claim 10, wherein the means for transferring heat from the heat absorbing material into a water circulation system consists of, a water transport pipe embedded in said heat absorbing material;   a tank connected to said water transport pipe to receive heated water therefrom;   a cold water feed pipe connecting to said water transport pipe to pass water to be heated thereto; and   a hot water line connected to said tank to receive heated water therefrom.   
     
     
       12. A furnace and heat storage assembly as recited in claim 11, wherein the tank is embedded in the heat absorbing material.